CN214256279U

CN214256279U - Output circuit, PCB and electronic device

Info

Publication number: CN214256279U
Application number: CN202023333268.7U
Authority: CN
Inventors: 胡卓敏; 刘园园; 韩莉勤; 杨春雷
Original assignee: Continental Automotive Body Electronic System Wuhu Co Ltd
Current assignee: Vitesco Automotive Wuhu Co Ltd; Continental Automotive Body Electronic System Wuhu Co Ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-09-21
Anticipated expiration: 2030-12-30

Abstract

The utility model provides an output circuit, include: a first input terminal PI1, a second input terminal PI2 and an output terminal PO; further comprising: a current limiting circuit CL and a switching circuit SW; the current limiting circuit CL includes a first resistor R1 and a transistor T1, a base and an emitter of the transistor T1 are respectively connected to two ends of the first resistor R1, and the voltage of the first resistor R1 can be clamped to the conduction voltage Vbe of the transistor T1, so that the output current is limited to be less than or equal to Vbe/R1. The utility model provides a PCB and electron device. The utility model provides an output circuit, PCB and electron device are connected to the both ends of resistance respectively with the base of triode and projecting pole, can clamp down the voltage of resistance at the conduction voltage of triode, and then with the scope of output current restriction at less than or equal to conduction voltage/resistance value.

Description

Output circuit, PCB and electronic device

Technical Field

The utility model relates to an automotive filed, concretely relates to output circuit, PCB and electron device.

Background

As shown in fig. 1, the output circuit in the meter includes a switching circuit SW and an integrated circuit chip IC for output protection, and the integrated circuit chip IC is expensive.

However, the output circuit usually used lacks effective current limiting protection, for example, a sensor of a plurality of connected external sensors is suddenly disconnected, so that the load becomes smaller, the current correspondingly becomes larger, and if no effective current limiting protection exists, the output circuit is damaged.

Disclosure of Invention

To the problem that exists among the prior art, the to-be-solved problem of the utility model is to provide an output circuit is connected to the both ends of resistance respectively with the base of triode and projecting pole, can clamp the voltage of resistance at the turn-on voltage of triode, and then with the scope of output current restriction at the less than or equal to turn-on voltage/resistance value.

By arranging the triode in the output circuit, when the output current is larger than a set value, the output current is smaller than or equal to the set value.

The utility model provides an output circuit, include:

a first input terminal PI1 for connecting a positive electrode of a power supply;

a second input terminal PI2 for inputting a control signal from the controller;

the output end PO is used for connecting an external module;

the output circuit further includes:

the current limiting circuit CL is used for limiting the magnitude of the output current and is connected with the output end PO;

the switching circuit SW is arranged between the first input end PI1 and the current limiting circuit CL, and a control end of the switching circuit SW is connected with the second input end PI 2;

the current limiting circuit CL includes a first resistor R1 and a transistor T1, a base and an emitter of the transistor T1 are respectively connected to two ends of the first resistor R1, and the voltage of the first resistor R1 can be clamped to the conduction voltage Vbe of the transistor T1, so that the output current is limited to be less than or equal to Vbe/R1.

Furthermore, the current limiting circuit CL further includes a second resistor R2 and a fet M1, the first resistor R1 is connected to the source of the fet M1, and the gate of the fet M1 is connected to the collector or emitter of the transistor T1 and is grounded through the second resistor R2.

Further, the transistor T1 is a PNP transistor or an NPN transistor.

Furthermore, the output circuit further comprises an acquisition circuit which comprises a voltage division circuit arranged between the output end PO and the ground, and the voltage division point VG _ MON is connected with an acquisition signal input end of the controller.

Further, a reverse protection circuit is arranged between the current limiting circuit CL and the output terminal PO.

Further, a filter circuit is arranged between the output end PO of the output circuit and the ground.

The utility model also provides a PCB, including controller and above-mentioned output circuit, the control signal output part of controller and output circuit's second input PI 2.

Furthermore, the acquisition signal input end of the controller is connected with the acquisition circuit of the output circuit.

The utility model also provides an electronic device, including above-mentioned PCB.

Further, the electronic device is a meter or an infotainment system.

Compared with the prior art, the utility model provides an output circuit, PCB and electron device has following beneficial effect: the base electrode and the emitting electrode of the triode are respectively connected to two ends of the resistor, so that the voltage of the resistor can be clamped at the conduction voltage of the triode, and the output current is limited within the range smaller than or equal to the conduction voltage/resistance value.

Drawings

FIG. 1 is a schematic diagram of an output circuit in the prior art;

fig. 2 is a schematic diagram of an output circuit of an embodiment of the present invention;

fig. 3 is a schematic diagram of an equivalent circuit of a current limiting circuit of the output circuit when the current does not exceed the upper limit.

Detailed Description

As shown in fig. 2, the output circuit of an embodiment of the present invention is used in an electronic device, such as a meter or an infotainment system, and the output circuit is disposed on a PCB, and includes a controller and the above output circuit, a control signal output terminal of the controller and a second input terminal PI2 of the output circuit.

The output circuit includes:

a first input terminal PI1 for connecting a power supply positive electrode VCC;

a second input terminal PI2 for inputting a control signal from the controller MCU;

and an output terminal PO for connecting an external module, such as a vehicle speed sensor, a control valve, etc.

The output circuit further includes:

the switching circuit SW is disposed between the first input terminal PI1 and the current limiting circuit CL, and a control terminal of the switching circuit SW is connected to the second input terminal PI 2.

The switching circuit SW includes a transistor T2 and a fet M2.

The source of the field effect transistor M2 is connected to the first input PI1, and is connected to the collector of the transistor T2 through the third resistor R3, the drain is connected to the current limiting circuit CL, and the gate G of the field effect transistor M2 is connected to the collector of the transistor T2 through the fourth resistor R4.

The base of the transistor T2 is connected to the second input terminal PI2 through a fifth resistor R5, and is grounded through a sixth resistor.

The second input terminal PI2 is a control terminal of the switching circuit SW.

The control signal output end of the controller outputs an effective control signal, the switching circuit SW is conducted, and the output current is output to the output end PO through the current limiting circuit CL and then is output to an external sensor or a control valve and the like.

In other embodiments, other switching circuits may be used, and the present invention is not limited thereto.

The current limiting circuit CL includes a first resistor R1, a second resistor R2, a field effect transistor M1 and a transistor T1, the first resistor R1 is connected to a source S of the field effect transistor M1, and a gate G of the field effect transistor M1 is connected to a collector or an emitter of the transistor T1 and is grounded through the second resistor R2.

And a reverse protection circuit is arranged between the current limiting circuit CL and the output end PO and is used for preventing external high voltage from being injected. In this embodiment, the reverse protection circuit is a diode D1, and the drain D of the fet M1 is connected to the output terminal PO via a diode D1.

A filter circuit is arranged between the output end PO of the output circuit and the ground. In this embodiment, the filter circuit is a capacitor C1.

The base and the emitter of the transistor T1 are connected to two ends of the first resistor R1, respectively.

When the current through the first resistor R1 is small, i.e., the voltage across the first resistor R1 is smaller than the on voltage Vbe of the transistor T1, the transistor T1 is turned off, as shown in fig. 3.

As the current passing through the first resistor R1 increases, the voltage across the first resistor R1 also gradually increases, and when the voltage increases to the on-voltage Vbe of the transistor T1, the transistor T1 is turned on, clamping the voltage of the first resistor R1 to the on-voltage Vbe of the transistor T1, and further limiting the current passing through the first resistor R1, i.e., the output current, to a range less than or equal to Vbe/R1, i.e., a range of on-voltage/resistance.

The transistor T1 is a PNP transistor or an NPN transistor, and in this embodiment, the transistor T1 is a PNP transistor.

The output circuit further comprises an acquisition circuit, the acquisition circuit comprises a voltage division circuit connected with the output end PO, the voltage division circuit comprises a seventh resistor R7 and an eighth resistor R8 which are connected in series, and a voltage division point (a connection point of the seventh resistor R7 and the eighth resistor R8) is connected with an acquisition signal input end of the controller.

When the load of the external sensor suddenly becomes smaller, the output current becomes larger, at this time, the output current is clamped due to the current limitation of the first resistor R1, when the current continues to increase, a voltage drop occurs on the field effect transistor M1, the output voltage is reduced, at this time, a corresponding alarm can be performed through the collected voltage VG _ MON or the switching circuit SW is controlled to be switched off, and the output to the external module is stopped.

The reason for the voltage drop of the field effect transistor M1 is: for example, if the sensor load is suddenly decreased and increased to 200MA, and the current of the load is limited to 100MA due to the current limiting circuit, the output voltage will decrease, the power voltage will not change, and the fet M1 will have a voltage drop to make it enter an amplifying state, which is not a desired fully conducting state.

When the external module is suddenly short-circuited for some reason, for example, the vehicle speed sensor is short-circuited to the ground, the voltage VG _ MON collected at this time is close to the ground voltage, a signal close to the ground voltage is collected through the collection signal input end of the controller MCU, and the controller MCU outputs a control signal from the control signal output end, so that the switching circuit SW is switched off, and the output circuit is protected.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited thereto. Various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is to be determined by the appended claims.

Claims

1. An output circuit, characterized in that the output circuit comprises:

a second input terminal PI2 for inputting a control signal from the controller;

the output end PO is used for connecting an external module;

the output circuit further includes:

2. The output circuit of claim 1, wherein the current limiting circuit CL further comprises a second resistor R2 and a fet M1, the first resistor R1 is connected to the source of the fet M1, and the gate of the fet M1 is connected to the collector or emitter of the transistor T1 and is connected to ground through a second resistor R2.

3. The output circuit of claim 2, wherein the transistor T1 is a PNP transistor or an NPN transistor.

4. The output circuit of claim 1, wherein the output circuit further comprises an acquisition circuit comprising a voltage divider circuit disposed between the output terminal PO and ground, the voltage divider point VG _ MON being connected to an acquisition signal input terminal of the controller.

5. The output circuit of claim 1, wherein a reverse protection circuit is disposed between the current limiting circuit CL and the output terminal PO.

6. The output circuit of claim 1, wherein a filter circuit is disposed between the output terminal PO of the output circuit and ground.

7. A PCB comprising a controller and an output circuit as claimed in any one of claims 1 to 6, a control signal output of the controller being coupled to the second input PI2 of the output circuit.

8. The PCB of claim 7, wherein the acquisition signal input of the controller is connected to the acquisition circuit of the output circuit.

9. An electronic device, characterized in that the electronic device comprises the PCB of claim 7 or 8.

10. The electronic device of claim 9, wherein the electronic device is a meter or an infotainment system.